The Proboscis monkey is an Old World monkey with a characteristic long nose that distinguishes this animal from other monkeys. As a matter of fact, another name of this primate is 'Monyet belanda' monkey, literally meaning 'long-nosed' monkey. When first seeing this animal, people didn't suppose it was a monkey because of its rather unusual appearance. Thus, males of this species exhibit extremely long noses of up to 7 inches, which are likely to attract females whose noses are usually shorter. Another important characteristic of Proboscis monkeys is their diverse color patterns, varying from bright orange to yellow or pink. Additionally, newborn Proboscis monkey display blue faces that turn to cream color as they grow up.
Diurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example, foliage, for the main component of its die...
Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some anima...
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Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
Polygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
A dominance hierarchy (formerly and colloquially called a pecking order) is a type of social hierarchy that arises when members of animal social gr...
NoNot a migrant
Animals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
These animals are native and endemic exclusively to the island of Borneo in southeastern Asia, where they generally live in coastal areas, covered with mangroves and swamp forests. Other suitable habitats include lowlands along rivers as well as riparian forests and rainforests. Proboscis monkeys typically live in close proximity to water bodies of their home range.
Proboscis monkeys are highly social animals, forming troops of 2-30 animals, typically consisting of a single dominant male and multiple (up to 10) females with their offspring. Males defend their group by exposing their teeth and emitting loud, honking signals, while females are responsible for foraging and caring for infants. In areas with sufficient food or close to the water, these troops may occasionally unite in larger aggregations. During these times, groups of Proboscis monkeys rest and sleep among mangroves at the edge of the water. The presence of freshwater bodies such as swamps or rivers is the primary life condition for these animals. Proboscis monkeys are accomplished swimmers. Moreover, when foraging or fleeing from a threat, they are able to take deep dives. Proboscis monkeys communicate with each other using various vocalizations. When claiming the status of the group, males will emit honks; they will also produce alarm calls to signal danger. Both sexes give threat calls, but each are different. In addition, females and immature individuals will emit so-called "female calls" when angry. These monkeys will also make honks, roars, and snarls. Nonvocal displays include leaping-branch shaking, and bare-teeth open mouth threats.
Proboscis monkeys have a polygynous mating system, where the dominant male mates with females in a troop. They breed between February and November. The gestation period lasts for 166 days, yielding one infant, typically during the nighttime hours. The newborn baby exhibits a deep blue face and sparse, almost black coat, which changes its color within 3-4 months after birth. Collective rearing is common in this species: females of a troop help raise each other's offspring. They can also suckle another female's young when needed. During the first year of its life, the infant is constantly with its mother. However, soon the female produces another baby, after which young females usually continue living with their natal group, whereas males disperse, joining all-male bachelor groups. The age of reproductive maturity is 4 years old in females and 4-5 years old in males.
Currently, the biggest threat to this species is the loss of their natural habitat as a result of forest fires and the cutting of mangrove trees, growing along riverbanks. Meanwhile, those in coastal areas lose their range due to the development of human settlements and shrimp farms. Another serious concern is localized hunting for food and intestinal bezoar stones, used in traditional medicine. This threat is compounded by the docile nature of these animals, making them 'easy prey' for hunters.
The IUCN Red List and other sources don’t provide the number of the Proboscis monkeys’ total population. However, according to the IUCN Red List, specific populations have been estimated in the following areas: Indonesia - population number in this country is associated with past and current threats, varying from less than 100 to more than 1,000 individuals; and Sarawak - population in this region is estimated to be less than 1,000 Proboscis monkeys. Overall, Proboscis monkeys’ numbers are decreasing today, and the animals are classified as Endangered (EN) on the IUCN Red List.